[GIT PULL] tracing: Fixes for v6.15

[GIT PULL] tracing: Fixes for v6.15

[Steven Rostedt]

Linus,

tracing fixes for v6.15

- Hide get_vm_area() from MMUless builds

  The function get_vm_area() is not defined when CONFIG_MMU is not defined.
  Hide that function within #ifdef CONFIG_MMU.

- Fix output of synthetic events when they have dynamic strings

  The print fmt of the synthetic event's format file use to have "%.*s" for
  dynamic size strings even though the user space exported arguments had
  only __get_str() macro that provided just a nul terminated string. This
  was fixed so that user space could parse this properly. But the reason
  that it had "%.*s" was because internally it provided the maximum size of
  the string as one of the arguments. The fix that replaced "%.*s" with "%s"
  caused the trace output (when the kernel reads the event) to write
  "(efault)" as it would now read the length of the string as "%s".

  As the string provided is always nul terminated, there's no reason for the
  internal code to use "%.*s" anyway. Just remove the length argument to
  match the "%s" that is now in the format.

- Fix the ftrace subops hash logic of the manager ops hash

  The function_graph uses the ftrace subops code. The subops code is a way
  to have a single ftrace_ops registered with ftrace to determine what
  functions will call the ftrace_ops callback. More than one user of
  function graph can register a ftrace_ops with it. The function graph
  infrastructure will then add this ftrace_ops as a subops with the main
  ftrace_ops it registers with ftrace. This is because the functions will
  always call the function graph callback which in turn calls the subops
  ftrace_ops callbacks.

  The main ftrace_ops must add a callback to all the functions that the
  subops want a callback from. When a subops is registered, it will update
  the main ftrace_ops hash to include the functions it wants. This is the
  logic that was broken.

  The ftrace_ops hash has a "filter_hash" and a "notrace_hash" were all the
  functions in the filter_hash but not in the notrace_hash are attached by
  ftrace. The original logic would have the main ftrace_ops filter_hash be a
  union of all the subops filter_hashes and the main notrace_hash would be a
  intersect of all the subops filter hashes. But this was incorrect because
  the notrace hash depends on the filter_hash it is associated to and not
  the union of all filter_hashes.

  Instead, when a subops is added, just include all the functions of the
  subops hash that are in its filter_hash but not in its notrace_hash. The
  main subops hash should not use its notrace hash, unless all of its subops
  hashes have an empty filter_hash (which means to attach to all functions),
  and then, and only then, the main ftrace_ops notrace hash can be the
  intersect of all the subops hashes.

  This not only fixes the bug, but also simplifies the code.

- Add a selftest to better test the subops filtering

  Add a selftest that would catch the bug fixed by the above change.

- Fix extra newline printed in function tracing with retval

  The function parameter code changed the output logic slightly and called
  print_graph_retval() and also printed a newline. The print_graph_retval()
  also prints a newline which caused blank lines to be printed in the
  function graph tracer when retval was added. This caused one of the
  selftests to fail if retvals were enabled. Instead remove the new line
  output from print_graph_retval() and have the callers always print the
  new line so that it doesn't have to do special logic if it calls
  print_graph_retval() or not.

- Fix out-of-bound memory access in the runtime verifier

  When rv_is_container_monitor() is called on the last entry on the link
  list it references the next entry, which is the list head and causes an
  out-of-bound memory access.


Please pull the latest trace-v6.15-rc1 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace-v6.15-rc1

Tag SHA1: bf44b733f8b5f9bcbe9c61acc958df8f3c7ad944
Head SHA1: 8d7861ac507d23024c7d74b6cb59a9cca248bcb7


Andy Chiu (1):
      ftrace: Properly merge notrace hashes

Nam Cao (1):
      rv: Fix out-of-bound memory access in rv_is_container_monitor()

Steven Rostedt (5):
      tracing: Hide get_vm_area() from MMUless builds
      tracing: Do not add length to print format in synthetic events
      ftrace: Fix accounting of subop hashes
      tracing/selftest: Add test to better test subops filtering of function graph
      ftrace: Do not have print_graph_retval() add a newline

----
 kernel/trace/ftrace.c                              | 314 ++++++++++++---------
 kernel/trace/rv/rv.c                               |   7 +-
 kernel/trace/trace.c                               |   7 +
 kernel/trace/trace_events_synth.c                  |   1 -
 kernel/trace/trace_functions_graph.c               |  11 +-
 .../ftrace/test.d/ftrace/fgraph-multi-filter.tc    | 177 ++++++++++++
 6 files changed, 372 insertions(+), 145 deletions(-)
 create mode 100644 tools/testing/selftests/ftrace/test.d/ftrace/fgraph-multi-filter.tc
---------------------------
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 1a48aedb5255..a8a02868b435 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3255,6 +3255,31 @@ static int append_hash(struct ftrace_hash **hash, struct ftrace_hash *new_hash,
 	return 0;
 }
 
+/*
+ * Remove functions from @hash that are in @notrace_hash
+ */
+static void remove_hash(struct ftrace_hash *hash, struct ftrace_hash *notrace_hash)
+{
+	struct ftrace_func_entry *entry;
+	struct hlist_node *tmp;
+	int size;
+	int i;
+
+	/* If the notrace hash is empty, there's nothing to do */
+	if (ftrace_hash_empty(notrace_hash))
+		return;
+
+	size = 1 << hash->size_bits;
+	for (i = 0; i < size; i++) {
+		hlist_for_each_entry_safe(entry, tmp, &hash->buckets[i], hlist) {
+			if (!__ftrace_lookup_ip(notrace_hash, entry->ip))
+				continue;
+			remove_hash_entry(hash, entry);
+			kfree(entry);
+		}
+	}
+}
+
 /*
  * Add to @hash only those that are in both @new_hash1 and @new_hash2
  *
@@ -3295,67 +3320,6 @@ static int intersect_hash(struct ftrace_hash **hash, struct ftrace_hash *new_has
 	return 0;
 }
 
-/* Return a new hash that has a union of all @ops->filter_hash entries */
-static struct ftrace_hash *append_hashes(struct ftrace_ops *ops)
-{
-	struct ftrace_hash *new_hash = NULL;
-	struct ftrace_ops *subops;
-	int size_bits;
-	int ret;
-
-	if (ops->func_hash->filter_hash)
-		size_bits = ops->func_hash->filter_hash->size_bits;
-	else
-		size_bits = FTRACE_HASH_DEFAULT_BITS;
-
-	list_for_each_entry(subops, &ops->subop_list, list) {
-		ret = append_hash(&new_hash, subops->func_hash->filter_hash, size_bits);
-		if (ret < 0) {
-			free_ftrace_hash(new_hash);
-			return NULL;
-		}
-		/* Nothing more to do if new_hash is empty */
-		if (ftrace_hash_empty(new_hash))
-			break;
-	}
-	/* Can't return NULL as that means this failed */
-	return new_hash ? : EMPTY_HASH;
-}
-
-/* Make @ops trace evenything except what all its subops do not trace */
-static struct ftrace_hash *intersect_hashes(struct ftrace_ops *ops)
-{
-	struct ftrace_hash *new_hash = NULL;
-	struct ftrace_ops *subops;
-	int size_bits;
-	int ret;
-
-	list_for_each_entry(subops, &ops->subop_list, list) {
-		struct ftrace_hash *next_hash;
-
-		if (!new_hash) {
-			size_bits = subops->func_hash->notrace_hash->size_bits;
-			new_hash = alloc_and_copy_ftrace_hash(size_bits, ops->func_hash->notrace_hash);
-			if (!new_hash)
-				return NULL;
-			continue;
-		}
-		size_bits = new_hash->size_bits;
-		next_hash = new_hash;
-		new_hash = alloc_ftrace_hash(size_bits);
-		ret = intersect_hash(&new_hash, next_hash, subops->func_hash->notrace_hash);
-		free_ftrace_hash(next_hash);
-		if (ret < 0) {
-			free_ftrace_hash(new_hash);
-			return NULL;
-		}
-		/* Nothing more to do if new_hash is empty */
-		if (ftrace_hash_empty(new_hash))
-			break;
-	}
-	return new_hash;
-}
-
 static bool ops_equal(struct ftrace_hash *A, struct ftrace_hash *B)
 {
 	struct ftrace_func_entry *entry;
@@ -3427,6 +3391,93 @@ static int ftrace_update_ops(struct ftrace_ops *ops, struct ftrace_hash *filter_
 	return 0;
 }
 
+static int add_first_hash(struct ftrace_hash **filter_hash, struct ftrace_hash **notrace_hash,
+			  struct ftrace_ops_hash *func_hash)
+{
+	/* If the filter hash is not empty, simply remove the nohash from it */
+	if (!ftrace_hash_empty(func_hash->filter_hash)) {
+		*filter_hash = copy_hash(func_hash->filter_hash);
+		if (!*filter_hash)
+			return -ENOMEM;
+		remove_hash(*filter_hash, func_hash->notrace_hash);
+		*notrace_hash = EMPTY_HASH;
+
+	} else {
+		*notrace_hash = copy_hash(func_hash->notrace_hash);
+		if (!*notrace_hash)
+			return -ENOMEM;
+		*filter_hash = EMPTY_HASH;
+	}
+	return 0;
+}
+
+static int add_next_hash(struct ftrace_hash **filter_hash, struct ftrace_hash **notrace_hash,
+			 struct ftrace_ops_hash *ops_hash, struct ftrace_ops_hash *subops_hash)
+{
+	int size_bits;
+	int ret;
+
+	/* If the subops trace all functions so must the main ops */
+	if (ftrace_hash_empty(ops_hash->filter_hash) ||
+	    ftrace_hash_empty(subops_hash->filter_hash)) {
+		*filter_hash = EMPTY_HASH;
+	} else {
+		/*
+		 * The main ops filter hash is not empty, so its
+		 * notrace_hash had better be, as the notrace hash
+		 * is only used for empty main filter hashes.
+		 */
+		WARN_ON_ONCE(!ftrace_hash_empty(ops_hash->notrace_hash));
+
+		size_bits = max(ops_hash->filter_hash->size_bits,
+				subops_hash->filter_hash->size_bits);
+
+		/* Copy the subops hash */
+		*filter_hash = alloc_and_copy_ftrace_hash(size_bits, subops_hash->filter_hash);
+		if (!filter_hash)
+			return -ENOMEM;
+		/* Remove any notrace functions from the copy */
+		remove_hash(*filter_hash, subops_hash->notrace_hash);
+
+		ret = append_hash(filter_hash, ops_hash->filter_hash,
+				  size_bits);
+		if (ret < 0) {
+			free_ftrace_hash(*filter_hash);
+			return ret;
+		}
+	}
+
+	/*
+	 * Only process notrace hashes if the main filter hash is empty
+	 * (tracing all functions), otherwise the filter hash will just
+	 * remove the notrace hash functions, and the notrace hash is
+	 * not needed.
+	 */
+	if (ftrace_hash_empty(*filter_hash)) {
+		/*
+		 * Intersect the notrace functions. That is, if two
+		 * subops are not tracing a set of functions, the
+		 * main ops will only not trace the functions that are
+		 * in both subops, but has to trace the functions that
+		 * are only notrace in one of the subops, for the other
+		 * subops to be able to trace them.
+		 */
+		size_bits = max(ops_hash->notrace_hash->size_bits,
+				subops_hash->notrace_hash->size_bits);
+		*notrace_hash = alloc_ftrace_hash(size_bits);
+		if (!*notrace_hash)
+			return -ENOMEM;
+
+		ret = intersect_hash(notrace_hash, ops_hash->notrace_hash,
+				     subops_hash->notrace_hash);
+		if (ret < 0) {
+			free_ftrace_hash(*notrace_hash);
+			return ret;
+		}
+	}
+	return 0;
+}
+
 /**
  * ftrace_startup_subops - enable tracing for subops of an ops
  * @ops: Manager ops (used to pick all the functions of its subops)
@@ -3443,7 +3494,6 @@ int ftrace_startup_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, int
 	struct ftrace_hash *notrace_hash;
 	struct ftrace_hash *save_filter_hash;
 	struct ftrace_hash *save_notrace_hash;
-	int size_bits;
 	int ret;
 
 	if (unlikely(ftrace_disabled))
@@ -3467,14 +3517,14 @@ int ftrace_startup_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, int
 
 	/* For the first subops to ops just enable it normally */
 	if (list_empty(&ops->subop_list)) {
-		/* Just use the subops hashes */
-		filter_hash = copy_hash(subops->func_hash->filter_hash);
-		notrace_hash = copy_hash(subops->func_hash->notrace_hash);
-		if (!filter_hash || !notrace_hash) {
-			free_ftrace_hash(filter_hash);
-			free_ftrace_hash(notrace_hash);
-			return -ENOMEM;
-		}
+
+		/* The ops was empty, should have empty hashes */
+		WARN_ON_ONCE(!ftrace_hash_empty(ops->func_hash->filter_hash));
+		WARN_ON_ONCE(!ftrace_hash_empty(ops->func_hash->notrace_hash));
+
+		ret = add_first_hash(&filter_hash, &notrace_hash, subops->func_hash);
+		if (ret < 0)
+			return ret;
 
 		save_filter_hash = ops->func_hash->filter_hash;
 		save_notrace_hash = ops->func_hash->notrace_hash;
@@ -3500,48 +3550,16 @@ int ftrace_startup_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, int
 
 	/*
 	 * Here there's already something attached. Here are the rules:
-	 *   o If either filter_hash is empty then the final stays empty
-	 *      o Otherwise, the final is a superset of both hashes
-	 *   o If either notrace_hash is empty then the final stays empty
-	 *      o Otherwise, the final is an intersection between the hashes
+	 *   If the new subops and main ops filter hashes are not empty:
+	 *     o Make a copy of the subops filter hash
+	 *     o Remove all functions in the nohash from it.
+	 *     o Add in the main hash filter functions
+	 *     o Remove any of these functions from the main notrace hash
 	 */
-	if (ftrace_hash_empty(ops->func_hash->filter_hash) ||
-	    ftrace_hash_empty(subops->func_hash->filter_hash)) {
-		filter_hash = EMPTY_HASH;
-	} else {
-		size_bits = max(ops->func_hash->filter_hash->size_bits,
-				subops->func_hash->filter_hash->size_bits);
-		filter_hash = alloc_and_copy_ftrace_hash(size_bits, ops->func_hash->filter_hash);
-		if (!filter_hash)
-			return -ENOMEM;
-		ret = append_hash(&filter_hash, subops->func_hash->filter_hash,
-				  size_bits);
-		if (ret < 0) {
-			free_ftrace_hash(filter_hash);
-			return ret;
-		}
-	}
-
-	if (ftrace_hash_empty(ops->func_hash->notrace_hash) ||
-	    ftrace_hash_empty(subops->func_hash->notrace_hash)) {
-		notrace_hash = EMPTY_HASH;
-	} else {
-		size_bits = max(ops->func_hash->filter_hash->size_bits,
-				subops->func_hash->filter_hash->size_bits);
-		notrace_hash = alloc_ftrace_hash(size_bits);
-		if (!notrace_hash) {
-			free_ftrace_hash(filter_hash);
-			return -ENOMEM;
-		}
 
-		ret = intersect_hash(&notrace_hash, ops->func_hash->filter_hash,
-				     subops->func_hash->filter_hash);
-		if (ret < 0) {
-			free_ftrace_hash(filter_hash);
-			free_ftrace_hash(notrace_hash);
-			return ret;
-		}
-	}
+	ret = add_next_hash(&filter_hash, &notrace_hash, ops->func_hash, subops->func_hash);
+	if (ret < 0)
+		return ret;
 
 	list_add(&subops->list, &ops->subop_list);
 
@@ -3557,6 +3575,42 @@ int ftrace_startup_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, int
 	return ret;
 }
 
+static int rebuild_hashes(struct ftrace_hash **filter_hash, struct ftrace_hash **notrace_hash,
+			  struct ftrace_ops *ops)
+{
+	struct ftrace_ops_hash temp_hash;
+	struct ftrace_ops *subops;
+	bool first = true;
+	int ret;
+
+	temp_hash.filter_hash = EMPTY_HASH;
+	temp_hash.notrace_hash = EMPTY_HASH;
+
+	list_for_each_entry(subops, &ops->subop_list, list) {
+		*filter_hash = EMPTY_HASH;
+		*notrace_hash = EMPTY_HASH;
+
+		if (first) {
+			ret = add_first_hash(filter_hash, notrace_hash, subops->func_hash);
+			if (ret < 0)
+				return ret;
+			first = false;
+		} else {
+			ret = add_next_hash(filter_hash, notrace_hash,
+					    &temp_hash, subops->func_hash);
+			if (ret < 0) {
+				free_ftrace_hash(temp_hash.filter_hash);
+				free_ftrace_hash(temp_hash.notrace_hash);
+				return ret;
+			}
+		}
+
+		temp_hash.filter_hash = *filter_hash;
+		temp_hash.notrace_hash = *notrace_hash;
+	}
+	return 0;
+}
+
 /**
  * ftrace_shutdown_subops - Remove a subops from a manager ops
  * @ops: A manager ops to remove @subops from
@@ -3605,14 +3659,9 @@ int ftrace_shutdown_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, in
 	}
 
 	/* Rebuild the hashes without subops */
-	filter_hash = append_hashes(ops);
-	notrace_hash = intersect_hashes(ops);
-	if (!filter_hash || !notrace_hash) {
-		free_ftrace_hash(filter_hash);
-		free_ftrace_hash(notrace_hash);
-		list_add(&subops->list, &ops->subop_list);
-		return -ENOMEM;
-	}
+	ret = rebuild_hashes(&filter_hash, &notrace_hash, ops);
+	if (ret < 0)
+		return ret;
 
 	ret = ftrace_update_ops(ops, filter_hash, notrace_hash);
 	if (ret < 0) {
@@ -3628,11 +3677,11 @@ int ftrace_shutdown_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, in
 
 static int ftrace_hash_move_and_update_subops(struct ftrace_ops *subops,
 					      struct ftrace_hash **orig_subhash,
-					      struct ftrace_hash *hash,
-					      int enable)
+					      struct ftrace_hash *hash)
 {
 	struct ftrace_ops *ops = subops->managed;
-	struct ftrace_hash **orig_hash;
+	struct ftrace_hash *notrace_hash;
+	struct ftrace_hash *filter_hash;
 	struct ftrace_hash *save_hash;
 	struct ftrace_hash *new_hash;
 	int ret;
@@ -3649,24 +3698,15 @@ static int ftrace_hash_move_and_update_subops(struct ftrace_ops *subops,
 		return -ENOMEM;
 	}
 
-	/* Create a new_hash to hold the ops new functions */
-	if (enable) {
-		orig_hash = &ops->func_hash->filter_hash;
-		new_hash = append_hashes(ops);
-	} else {
-		orig_hash = &ops->func_hash->notrace_hash;
-		new_hash = intersect_hashes(ops);
-	}
-
-	/* Move the hash over to the new hash */
-	ret = __ftrace_hash_move_and_update_ops(ops, orig_hash, new_hash, enable);
-
-	free_ftrace_hash(new_hash);
+	ret = rebuild_hashes(&filter_hash, &notrace_hash, ops);
+	if (!ret)
+		ret = ftrace_update_ops(ops, filter_hash, notrace_hash);
 
 	if (ret) {
 		/* Put back the original hash */
-		free_ftrace_hash_rcu(*orig_subhash);
+		new_hash = *orig_subhash;
 		*orig_subhash = save_hash;
+		free_ftrace_hash_rcu(new_hash);
 	} else {
 		free_ftrace_hash_rcu(save_hash);
 	}
@@ -4890,7 +4930,7 @@ static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops,
 					   int enable)
 {
 	if (ops->flags & FTRACE_OPS_FL_SUBOP)
-		return ftrace_hash_move_and_update_subops(ops, orig_hash, hash, enable);
+		return ftrace_hash_move_and_update_subops(ops, orig_hash, hash);
 
 	/*
 	 * If this ops is not enabled, it could be sharing its filters
@@ -4909,7 +4949,7 @@ static int ftrace_hash_move_and_update_ops(struct ftrace_ops *ops,
 			list_for_each_entry(subops, &op->subop_list, list) {
 				if ((subops->flags & FTRACE_OPS_FL_ENABLED) &&
 				     subops->func_hash == ops->func_hash) {
-					return ftrace_hash_move_and_update_subops(subops, orig_hash, hash, enable);
+					return ftrace_hash_move_and_update_subops(subops, orig_hash, hash);
 				}
 			}
 		} while_for_each_ftrace_op(op);
diff --git a/kernel/trace/rv/rv.c b/kernel/trace/rv/rv.c
index 968c5c3b0246..e4077500a91d 100644
--- a/kernel/trace/rv/rv.c
+++ b/kernel/trace/rv/rv.c
@@ -225,7 +225,12 @@ bool rv_is_nested_monitor(struct rv_monitor_def *mdef)
  */
 bool rv_is_container_monitor(struct rv_monitor_def *mdef)
 {
-	struct rv_monitor_def *next = list_next_entry(mdef, list);
+	struct rv_monitor_def *next;
+
+	if (list_is_last(&mdef->list, &rv_monitors_list))
+		return false;
+
+	next = list_next_entry(mdef, list);
 
 	return next->parent == mdef->monitor || !mdef->monitor->enable;
 }
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index b581e388a9d9..8ddf6b17215c 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9806,6 +9806,7 @@ static int instance_mkdir(const char *name)
 	return ret;
 }
 
+#ifdef CONFIG_MMU
 static u64 map_pages(unsigned long start, unsigned long size)
 {
 	unsigned long vmap_start, vmap_end;
@@ -9828,6 +9829,12 @@ static u64 map_pages(unsigned long start, unsigned long size)
 
 	return (u64)vmap_start;
 }
+#else
+static inline u64 map_pages(unsigned long start, unsigned long size)
+{
+	return 0;
+}
+#endif
 
 /**
  * trace_array_get_by_name - Create/Lookup a trace array, given its name.
diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index 969f48742d72..33cfbd4ed76d 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -370,7 +370,6 @@ static enum print_line_t print_synth_event(struct trace_iterator *iter,
 				union trace_synth_field *data = &entry->fields[n_u64];
 
 				trace_seq_printf(s, print_fmt, se->fields[i]->name,
-						 STR_VAR_LEN_MAX,
 						 (char *)entry + data->as_dynamic.offset,
 						 i == se->n_fields - 1 ? "" : " ");
 				n_u64++;
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 2f077d4158e5..0c357a89c58e 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -880,8 +880,6 @@ static void print_graph_retval(struct trace_seq *s, struct ftrace_graph_ent_entr
 
 		if (print_retval || print_retaddr)
 			trace_seq_puts(s, " /*");
-		else
-			trace_seq_putc(s, '\n');
 	} else {
 		print_retaddr = false;
 		trace_seq_printf(s, "} /* %ps", func);
@@ -899,7 +897,7 @@ static void print_graph_retval(struct trace_seq *s, struct ftrace_graph_ent_entr
 	}
 
 	if (!entry || print_retval || print_retaddr)
-		trace_seq_puts(s, " */\n");
+		trace_seq_puts(s, " */");
 }
 
 #else
@@ -975,7 +973,7 @@ print_graph_entry_leaf(struct trace_iterator *iter,
 		} else
 			trace_seq_puts(s, "();");
 	}
-	trace_seq_printf(s, "\n");
+	trace_seq_putc(s, '\n');
 
 	print_graph_irq(iter, graph_ret->func, TRACE_GRAPH_RET,
 			cpu, iter->ent->pid, flags);
@@ -1313,10 +1311,11 @@ print_graph_return(struct ftrace_graph_ret_entry *retentry, struct trace_seq *s,
 		 * that if the funcgraph-tail option is enabled.
 		 */
 		if (func_match && !(flags & TRACE_GRAPH_PRINT_TAIL))
-			trace_seq_puts(s, "}\n");
+			trace_seq_puts(s, "}");
 		else
-			trace_seq_printf(s, "} /* %ps */\n", (void *)func);
+			trace_seq_printf(s, "} /* %ps */", (void *)func);
 	}
+	trace_seq_putc(s, '\n');
 
 	/* Overrun */
 	if (flags & TRACE_GRAPH_PRINT_OVERRUN)
diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-multi-filter.tc b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-multi-filter.tc
new file mode 100644
index 000000000000..b6d6a312ead5
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-multi-filter.tc
@@ -0,0 +1,177 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: ftrace - function graph filters
+# requires: set_ftrace_filter function_graph:tracer
+
+# Make sure that function graph filtering works
+
+INSTANCE1="instances/test1_$$"
+INSTANCE2="instances/test2_$$"
+
+WD=`pwd`
+
+do_reset() {
+    cd $WD
+    if [ -d $INSTANCE1 ]; then
+	echo nop > $INSTANCE1/current_tracer
+	rmdir $INSTANCE1
+    fi
+    if [ -d $INSTANCE2 ]; then
+	echo nop > $INSTANCE2/current_tracer
+	rmdir $INSTANCE2
+    fi
+}
+
+mkdir $INSTANCE1
+if ! grep -q function_graph $INSTANCE1/available_tracers; then
+    echo "function_graph not allowed with instances"
+    rmdir $INSTANCE1
+    exit_unsupported
+fi
+
+mkdir $INSTANCE2
+
+fail() { # msg
+    do_reset
+    echo $1
+    exit_fail
+}
+
+disable_tracing
+clear_trace
+
+function_count() {
+    search=$1
+    vsearch=$2
+
+    if [ -z "$search" ]; then
+	cat enabled_functions | wc -l
+    elif [ -z "$vsearch" ]; then
+	grep $search enabled_functions | wc -l
+    else
+	grep $search enabled_functions | grep $vsearch| wc -l
+    fi
+}
+
+set_fgraph() {
+    instance=$1
+    filter="$2"
+    notrace="$3"
+
+    echo "$filter" > $instance/set_ftrace_filter
+    echo "$notrace" > $instance/set_ftrace_notrace
+    echo function_graph > $instance/current_tracer
+}
+
+check_functions() {
+    orig_cnt=$1
+    test=$2
+
+    cnt=`function_count $test`
+    if [ $cnt -gt $orig_cnt ]; then
+	fail
+    fi
+}
+
+check_cnt() {
+    orig_cnt=$1
+    search=$2
+    vsearch=$3
+
+    cnt=`function_count $search $vsearch`
+    if [ $cnt -gt $orig_cnt ]; then
+	fail
+    fi
+}
+
+reset_graph() {
+    instance=$1
+    echo nop > $instance/current_tracer
+}
+
+# get any functions that were enabled before the test
+total_cnt=`function_count`
+sched_cnt=`function_count sched`
+lock_cnt=`function_count lock`
+time_cnt=`function_count time`
+clock_cnt=`function_count clock`
+locks_clock_cnt=`function_count locks clock`
+clock_locks_cnt=`function_count clock locks`
+
+# Trace functions with "sched" but not "time"
+set_fgraph $INSTANCE1 '*sched*' '*time*'
+
+# Make sure "time" isn't listed
+check_functions $time_cnt 'time'
+instance1_cnt=`function_count`
+
+# Trace functions with "lock" but not "clock"
+set_fgraph $INSTANCE2 '*lock*' '*clock*'
+instance1_2_cnt=`function_count`
+
+# Turn off the first instance
+reset_graph $INSTANCE1
+
+# The second instance doesn't trace "clock" functions
+check_functions $clock_cnt 'clock'
+instance2_cnt=`function_count`
+
+# Start from a clean slate
+reset_graph $INSTANCE2
+check_functions $total_cnt
+
+# Trace functions with "lock" but not "clock"
+set_fgraph $INSTANCE2 '*lock*' '*clock*'
+
+# This should match the last time instance 2 was by itself
+cnt=`function_count`
+if [ $instance2_cnt -ne $cnt ]; then
+    fail
+fi
+
+# And it should not be tracing "clock" functions
+check_functions $clock_cnt 'clock'
+
+# Trace functions with "sched" but not "time"
+set_fgraph $INSTANCE1 '*sched*' '*time*'
+
+# This should match the last time both instances were enabled
+cnt=`function_count`
+if [ $instance1_2_cnt -ne $cnt ]; then
+    fail
+fi
+
+# Turn off the second instance
+reset_graph $INSTANCE2
+
+# This should match the last time instance 1 was by itself
+cnt=`function_count`
+if [ $instance1_cnt -ne $cnt ]; then
+    fail
+fi
+
+# And it should not be tracing "time" functions
+check_functions $time_cnt 'time'
+
+# Start from a clean slate
+reset_graph $INSTANCE1
+check_functions $total_cnt
+
+# Enable all functions but those that have "locks"
+set_fgraph $INSTANCE1 '' '*locks*'
+
+# Enable all functions but those that have "clock"
+set_fgraph $INSTANCE2 '' '*clock*'
+
+# If a function has "locks" it should not have "clock"
+check_cnt $locks_clock_cnt locks clock
+
+# If a function has "clock" it should not have "locks"
+check_cnt $clock_locks_cnt clock locks
+
+reset_graph $INSTANCE1
+reset_graph $INSTANCE2
+
+do_reset
+
+exit 0

Re: [GIT PULL] tracing: Fixes for v6.15

[pr-tracker-bot]

The pull request you sent on Sat, 12 Apr 2025 17:15:14 -0400:

> git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git trace-v6.15-rc1

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/7cdabafc001202de9984f22c973305f424e0a8b7

Thank you!

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[GIT PULL] tracing: Fixes for v6.15

[Steven Rostedt]

Linus,

tracing fixes for v6.15

- Initialize hash variables in ftrace subops logic

  The fix that simplified the ftrace subops logic opened a path where some
  variables could be used without being initialized, and done subtly where
  the compiler did not catch it. Initialize those variables to the
  EMPTY_HASH, which is the default hash.

- Reinitialize the hash pointers after they are freed

  Some of the hash pointers in the subop logic were freed but may still be
  referenced later. To prevent use-after-free bugs, initialize them back to
  the EMPTY_HASH.

- Free the ftrace hashes when they are replaced

  The fix that simplified the subops logic updated some hash pointers, but
  left the original hash that they were pointing to where they are no longer
  used. This caused a memory leak. Free the hashes that are pointed to by
  the pointers when they are replaced.

- Fix size initialization of ftrace direct function hash

  The ftrace direct function hash used by BPF initialized the hash size
  incorrectly. It checked the size of items to a hard coded 32, which made
  the hash bit size of 5. The hash size is supposed to be limited by the bit
  size of the hash, as the bitmask is allowed to be greater than 5. Rework
  the size check to first pass the number of elements to fls() and then
  compare that to FTRACE_HASH_MAX_BITS before allocating the hash.

- Fix format output of ftrace_graph_ent_entry event

  The field depth of the ftrace_graph_ent_entry event is of size 4 but the
  output showed it as unsigned long and use "%lu". Change it to unsigned int
  and use "%u" in the print format that is displayed to user space.

- Fix the trace event filter on strings

  Events can be filtered on numbers or string values. The return value
  checked from strncpy_from_kernel_nofault() and strncpy_from_user_nofault()
  was used to determine if reading the strings would fault or not. It would
  return fault if the value was non zero, which basically meant that it
  was always considering the read as a fault.

- Add selftest to test trace event string filtering

  In order to catch the breakage of the string filtering, add a self test to
  make sure that it continues to work.


Please pull the latest trace-v6.15-rc2 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace-v6.15-rc2

Tag SHA1: d35e39873a50c9cae63eddfa79ab3e5d545de69a
Head SHA1: d481ee35247d2a01764667a25f6f512c292ba42d


Ilya Leoshkevich (1):
      ftrace: Fix type of ftrace_graph_ent_entry.depth

Menglong Dong (1):
      ftrace: fix incorrect hash size in register_ftrace_direct()

Steven Rostedt (5):
      ftrace: Initialize variables for ftrace_startup/shutdown_subops()
      ftrace: Reinitialize hash to EMPTY_HASH after freeing
      ftrace: Free ftrace hashes after they are replaced in the subops code
      tracing: Fix filter string testing
      tracing: selftests: Add testing a user string to filters

----
 kernel/trace/ftrace.c                              | 27 +++++++++++++++-------
 kernel/trace/trace_entries.h                       |  4 ++--
 kernel/trace/trace_events_filter.c                 |  4 ++--
 .../ftrace/test.d/filter/event-filter-function.tc  | 20 ++++++++++++++++
 4 files changed, 43 insertions(+), 12 deletions(-)
---------------------------
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index a8a02868b435..61130bb34d6c 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -1297,6 +1297,8 @@ void ftrace_free_filter(struct ftrace_ops *ops)
 		return;
 	free_ftrace_hash(ops->func_hash->filter_hash);
 	free_ftrace_hash(ops->func_hash->notrace_hash);
+	ops->func_hash->filter_hash = EMPTY_HASH;
+	ops->func_hash->notrace_hash = EMPTY_HASH;
 }
 EXPORT_SYMBOL_GPL(ftrace_free_filter);
 
@@ -3443,6 +3445,7 @@ static int add_next_hash(struct ftrace_hash **filter_hash, struct ftrace_hash **
 				  size_bits);
 		if (ret < 0) {
 			free_ftrace_hash(*filter_hash);
+			*filter_hash = EMPTY_HASH;
 			return ret;
 		}
 	}
@@ -3472,6 +3475,7 @@ static int add_next_hash(struct ftrace_hash **filter_hash, struct ftrace_hash **
 				     subops_hash->notrace_hash);
 		if (ret < 0) {
 			free_ftrace_hash(*notrace_hash);
+			*notrace_hash = EMPTY_HASH;
 			return ret;
 		}
 	}
@@ -3490,8 +3494,8 @@ static int add_next_hash(struct ftrace_hash **filter_hash, struct ftrace_hash **
  */
 int ftrace_startup_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, int command)
 {
-	struct ftrace_hash *filter_hash;
-	struct ftrace_hash *notrace_hash;
+	struct ftrace_hash *filter_hash = EMPTY_HASH;
+	struct ftrace_hash *notrace_hash = EMPTY_HASH;
 	struct ftrace_hash *save_filter_hash;
 	struct ftrace_hash *save_notrace_hash;
 	int ret;
@@ -3605,6 +3609,9 @@ static int rebuild_hashes(struct ftrace_hash **filter_hash, struct ftrace_hash *
 			}
 		}
 
+		free_ftrace_hash(temp_hash.filter_hash);
+		free_ftrace_hash(temp_hash.notrace_hash);
+
 		temp_hash.filter_hash = *filter_hash;
 		temp_hash.notrace_hash = *notrace_hash;
 	}
@@ -3625,8 +3632,8 @@ static int rebuild_hashes(struct ftrace_hash **filter_hash, struct ftrace_hash *
  */
 int ftrace_shutdown_subops(struct ftrace_ops *ops, struct ftrace_ops *subops, int command)
 {
-	struct ftrace_hash *filter_hash;
-	struct ftrace_hash *notrace_hash;
+	struct ftrace_hash *filter_hash = EMPTY_HASH;
+	struct ftrace_hash *notrace_hash = EMPTY_HASH;
 	int ret;
 
 	if (unlikely(ftrace_disabled))
@@ -3699,8 +3706,11 @@ static int ftrace_hash_move_and_update_subops(struct ftrace_ops *subops,
 	}
 
 	ret = rebuild_hashes(&filter_hash, &notrace_hash, ops);
-	if (!ret)
+	if (!ret) {
 		ret = ftrace_update_ops(ops, filter_hash, notrace_hash);
+		free_ftrace_hash(filter_hash);
+		free_ftrace_hash(notrace_hash);
+	}
 
 	if (ret) {
 		/* Put back the original hash */
@@ -5954,9 +5964,10 @@ int register_ftrace_direct(struct ftrace_ops *ops, unsigned long addr)
 
 	/* Make a copy hash to place the new and the old entries in */
 	size = hash->count + direct_functions->count;
-	if (size > 32)
-		size = 32;
-	new_hash = alloc_ftrace_hash(fls(size));
+	size = fls(size);
+	if (size > FTRACE_HASH_MAX_BITS)
+		size = FTRACE_HASH_MAX_BITS;
+	new_hash = alloc_ftrace_hash(size);
 	if (!new_hash)
 		goto out_unlock;
 
diff --git a/kernel/trace/trace_entries.h b/kernel/trace/trace_entries.h
index ee40d4e6ad1c..4ef4df6623a8 100644
--- a/kernel/trace/trace_entries.h
+++ b/kernel/trace/trace_entries.h
@@ -80,11 +80,11 @@ FTRACE_ENTRY(funcgraph_entry, ftrace_graph_ent_entry,
 	F_STRUCT(
 		__field_struct(	struct ftrace_graph_ent,	graph_ent	)
 		__field_packed(	unsigned long,	graph_ent,	func		)
-		__field_packed(	unsigned long,	graph_ent,	depth		)
+		__field_packed(	unsigned int,	graph_ent,	depth		)
 		__dynamic_array(unsigned long,	args				)
 	),
 
-	F_printk("--> %ps (%lu)", (void *)__entry->func, __entry->depth)
+	F_printk("--> %ps (%u)", (void *)__entry->func, __entry->depth)
 );
 
 #ifdef CONFIG_FUNCTION_GRAPH_RETADDR
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index 0993dfc1c5c1..2048560264bb 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -808,7 +808,7 @@ static __always_inline char *test_string(char *str)
 	kstr = ubuf->buffer;
 
 	/* For safety, do not trust the string pointer */
-	if (!strncpy_from_kernel_nofault(kstr, str, USTRING_BUF_SIZE))
+	if (strncpy_from_kernel_nofault(kstr, str, USTRING_BUF_SIZE) < 0)
 		return NULL;
 	return kstr;
 }
@@ -827,7 +827,7 @@ static __always_inline char *test_ustring(char *str)
 
 	/* user space address? */
 	ustr = (char __user *)str;
-	if (!strncpy_from_user_nofault(kstr, ustr, USTRING_BUF_SIZE))
+	if (strncpy_from_user_nofault(kstr, ustr, USTRING_BUF_SIZE) < 0)
 		return NULL;
 
 	return kstr;
diff --git a/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc b/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc
index 118247b8dd84..c62165fabd0c 100644
--- a/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc
+++ b/tools/testing/selftests/ftrace/test.d/filter/event-filter-function.tc
@@ -80,6 +80,26 @@ if [ $misscnt -gt 0 ]; then
 	exit_fail
 fi
 
+# Check strings too
+if [ -f events/syscalls/sys_enter_openat/filter ]; then
+	DIRNAME=`basename $TMPDIR`
+	echo "filename.ustring ~ \"*$DIRNAME*\"" > events/syscalls/sys_enter_openat/filter
+	echo 1 > events/syscalls/sys_enter_openat/enable
+	echo 1 > tracing_on
+	ls /bin/sh
+	nocnt=`grep openat trace | wc -l`
+	ls $TMPDIR
+	echo 0 > tracing_on
+	hitcnt=`grep openat trace | wc -l`;
+	echo 0 > events/syscalls/sys_enter_openat/enable
+	if [ $nocnt -gt 0 ]; then
+		exit_fail
+	fi
+	if [ $hitcnt -eq 0 ]; then
+		exit_fail
+	fi
+fi
+
 reset_events_filter
 
 exit 0

Re: [GIT PULL] tracing: Fixes for v6.15

[pr-tracker-bot]

The pull request you sent on Sat, 19 Apr 2025 14:28:42 -0400:

> git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git trace-v6.15-rc2

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/fa6ad96dca040e169f4008637d8d77f22631b34d

Thank you!

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[GIT PULL] tracing: Fixes for v6.15

[Steven Rostedt]

Linus,

tracing updates for v6.15

- Fix read out of bounds bug in tracing_splice_read_pipe()

  The size of the sub page being read can now be greater than a page. But
  the buffer used in tracing_splice_read_pipe() only allocates a page size.
  The data copied to the buffer is the amount in sub buffer which can
  overflow the buffer. Use min((size_t)trace_seq_used(&iter->seq), PAGE_SIZE)
  to limit the amount copied to the buffer to a max of PAGE_SIZE.

- Fix the test for NULL from "!filter_hash" to "!*filter_hash"

  The add_next_hash() function checked for NULL at the wrong pointer level.

- Do not use the array in trace_adjust_address() if there are no elements

  The trace_adjust_address() finds the offset of a module that was stored in
  the persistent buffer when reading the previous boot buffer to see if the
  address belongs to a module that was loaded in the previous boot. An array
  is created that matches currently loaded modules with previously loaded
  modules. The trace_adjust_address() uses that array to find the new offset
  of the address that's in the previous buffer.  But if no module was
  loaded, it ends up reading the last element in an array that was never
  allocated. Check if nr_entries is zero and exit out early if it is.

- Remove nested lock of trace_event_sem in print_event_fields()

  The print_event_fields() function iterates over the ftrace_events list and
  requires the trace_event_sem semaphore held for read. But this function is
  always called with that semaphore held for read. Remove the taking of the
  semaphore and replace it with lockdep_assert_held_read(&trace_event_sem);


Please pull the latest trace-v6.15-rc4 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace-v6.15-rc4

Tag SHA1: b2e4a898d100e7baf9a77ad9dbab05b7f63e4940
Head SHA1: 0a8f11f8569e7ed16cbcedeb28c4350f6378fea6


Colin Ian King (1):
      ftrace: Fix NULL memory allocation check

Jeongjun Park (1):
      tracing: Fix oob write in trace_seq_to_buffer()

Steven Rostedt (2):
      tracing: Fix trace_adjust_address() when there is no modules in scratch area
      tracing: Do not take trace_event_sem in print_event_fields()

----
 kernel/trace/ftrace.c       | 2 +-
 kernel/trace/trace.c        | 9 ++++++---
 kernel/trace/trace_output.c | 4 ++--
 3 files changed, 9 insertions(+), 6 deletions(-)
---------------------------
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 61130bb34d6c..6981830c3128 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3436,7 +3436,7 @@ static int add_next_hash(struct ftrace_hash **filter_hash, struct ftrace_hash **
 
 		/* Copy the subops hash */
 		*filter_hash = alloc_and_copy_ftrace_hash(size_bits, subops_hash->filter_hash);
-		if (!filter_hash)
+		if (!*filter_hash)
 			return -ENOMEM;
 		/* Remove any notrace functions from the copy */
 		remove_hash(*filter_hash, subops_hash->notrace_hash);
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 8ddf6b17215c..5b8db27fb6ef 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -6043,8 +6043,10 @@ unsigned long trace_adjust_address(struct trace_array *tr, unsigned long addr)
 	tscratch = tr->scratch;
 	/* if there is no tscrach, module_delta must be NULL. */
 	module_delta = READ_ONCE(tr->module_delta);
-	if (!module_delta || tscratch->entries[0].mod_addr > addr)
+	if (!module_delta || !tscratch->nr_entries ||
+	    tscratch->entries[0].mod_addr > addr) {
 		return addr + tr->text_delta;
+	}
 
 	/* Note that entries must be sorted. */
 	nr_entries = tscratch->nr_entries;
@@ -6821,13 +6823,14 @@ static ssize_t tracing_splice_read_pipe(struct file *filp,
 		/* Copy the data into the page, so we can start over. */
 		ret = trace_seq_to_buffer(&iter->seq,
 					  page_address(spd.pages[i]),
-					  trace_seq_used(&iter->seq));
+					  min((size_t)trace_seq_used(&iter->seq),
+						  PAGE_SIZE));
 		if (ret < 0) {
 			__free_page(spd.pages[i]);
 			break;
 		}
 		spd.partial[i].offset = 0;
-		spd.partial[i].len = trace_seq_used(&iter->seq);
+		spd.partial[i].len = ret;
 
 		trace_seq_init(&iter->seq);
 	}
diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
index fee40ffbd490..b9ab06c99543 100644
--- a/kernel/trace/trace_output.c
+++ b/kernel/trace/trace_output.c
@@ -1042,11 +1042,12 @@ enum print_line_t print_event_fields(struct trace_iterator *iter,
 	struct trace_event_call *call;
 	struct list_head *head;
 
+	lockdep_assert_held_read(&trace_event_sem);
+
 	/* ftrace defined events have separate call structures */
 	if (event->type <= __TRACE_LAST_TYPE) {
 		bool found = false;
 
-		down_read(&trace_event_sem);
 		list_for_each_entry(call, &ftrace_events, list) {
 			if (call->event.type == event->type) {
 				found = true;
@@ -1056,7 +1057,6 @@ enum print_line_t print_event_fields(struct trace_iterator *iter,
 			if (call->event.type > __TRACE_LAST_TYPE)
 				break;
 		}
-		up_read(&trace_event_sem);
 		if (!found) {
 			trace_seq_printf(&iter->seq, "UNKNOWN TYPE %d\n", event->type);
 			goto out;

Re: [GIT PULL] tracing: Fixes for v6.15

[pr-tracker-bot]

The pull request you sent on Sun, 4 May 2025 12:39:21 -0400:

> git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git trace-v6.15-rc4

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/59c9ab3e8cc7f56cd65608f6e938b5ae96eb9cd2

Thank you!

-- 
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Re: [GIT PULL] tracing: Fixes for v6.15

[pr-tracker-bot]

The pull request you sent on Sun, 4 May 2025 12:39:21 -0400:

> git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git trace-v6.15-rc4

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/59c9ab3e8cc7f56cd65608f6e938b5ae96eb9cd2

Thank you!

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[GIT PULL] tracing: Fixes for v6.15

[Steven Rostedt]

Linus,

tracing fixes for 6.15:

- Fix sample code that uses trace_array_printk()

  The sample code for in kernel use of trace_array (that creates an instance
  for use within the kernel) and shows how to use trace_array_printk() that
  writes into the created instance, used trace_printk_init_buffers(). But
  that function is used to initialize normal trace_printk() and produces the
  NOTICE banner which is not needed for use of trace_array_printk(). The
  function to initialize that is trace_array_init_printk() that takes the
  created trace array instance as a parameter.

  Update the sample code to reflect the proper usage.

- Fix preemption count output for stacktrace event

  The tracing buffer shows the preempt count level when an event executes.
  Because writing the event itself disables preemption, this needs to be
  accounted for when recording. The stacktrace event did not account for
  this so the output of the stacktrace event showed preemption was disabled
  while the event that triggered the stacktrace shows preemption is enabled
  and this leads to confusion. Account for preemption being disabled for the
  stacktrace event.

  The same happened for stack traces triggered by function tracer.

- Fix persistent ring buffer when trace_pipe is used

  The ring buffer swaps the reader page with the next page to read from the
  write buffer when trace_pipe is used. If there's only a page of data in
  the ring buffer, this swap will cause the "commit" pointer (last data
  written) to be on the reader page. If more data is written to the buffer,
  it is added to the reader page until it falls off back into the write
  buffer.

  If the system reboots and the commit pointer is still on the reader page,
  even if new data was written, the persistent buffer validator will miss
  finding the commit pointer because it only checks the write buffer and
  does not check the reader page. This causes the validator to fail the
  validation and clear the buffer, where the new data is lost.

  There was a check for this, but it checked the "head pointer", which was
  incorrect, because the "head pointer" always stays on the write buffer and
  is the next page to swap out for the reader page. Fix the logic to catch
  this case and allow the user to still read the data after reboot.


Please pull the latest trace-v6.15-rc6 tree, which can be found at:


  git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
trace-v6.15-rc6

Tag SHA1: b5e2f786d078bcc3bf257edafb92ed180c8bfb26
Head SHA1: 1d6c39c89f617c9fec6bbae166e25b16a014f7c8


Steven Rostedt (2):
      tracing: samples: Initialize trace_array_printk() with the correct function
      ring-buffer: Fix persistent buffer when commit page is the reader page

pengdonglin (2):
      ftrace: Fix preemption accounting for stacktrace trigger command
      ftrace: Fix preemption accounting for stacktrace filter command

----
 kernel/trace/ring_buffer.c          | 8 +++++---
 kernel/trace/trace_events_trigger.c | 2 +-
 kernel/trace/trace_functions.c      | 6 +-----
 samples/ftrace/sample-trace-array.c | 2 +-
 4 files changed, 8 insertions(+), 10 deletions(-)
---------------------------
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c
index c0f877d39a24..3f9bf562beea 100644
--- a/kernel/trace/ring_buffer.c
+++ b/kernel/trace/ring_buffer.c
@@ -1887,10 +1887,12 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer)
 
 	head_page = cpu_buffer->head_page;
 
-	/* If both the head and commit are on the reader_page then we are done. */
-	if (head_page == cpu_buffer->reader_page &&
-	    head_page == cpu_buffer->commit_page)
+	/* If the commit_buffer is the reader page, update the commit page */
+	if (meta->commit_buffer == (unsigned long)cpu_buffer->reader_page->page) {
+		cpu_buffer->commit_page = cpu_buffer->reader_page;
+		/* Nothing more to do, the only page is the reader page */
 		goto done;
+	}
 
 	/* Iterate until finding the commit page */
 	for (i = 0; i < meta->nr_subbufs + 1; i++, rb_inc_page(&head_page)) {
diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index b66b6d235d91..6e87ae2a1a66 100644
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -1560,7 +1560,7 @@ stacktrace_trigger(struct event_trigger_data *data,
 	struct trace_event_file *file = data->private_data;
 
 	if (file)
-		__trace_stack(file->tr, tracing_gen_ctx(), STACK_SKIP);
+		__trace_stack(file->tr, tracing_gen_ctx_dec(), STACK_SKIP);
 	else
 		trace_dump_stack(STACK_SKIP);
 }
diff --git a/kernel/trace/trace_functions.c b/kernel/trace/trace_functions.c
index 98ccf3f00c51..4e37a0f6aaa3 100644
--- a/kernel/trace/trace_functions.c
+++ b/kernel/trace/trace_functions.c
@@ -633,11 +633,7 @@ ftrace_traceoff(unsigned long ip, unsigned long parent_ip,
 
 static __always_inline void trace_stack(struct trace_array *tr)
 {
-	unsigned int trace_ctx;
-
-	trace_ctx = tracing_gen_ctx();
-
-	__trace_stack(tr, trace_ctx, FTRACE_STACK_SKIP);
+	__trace_stack(tr, tracing_gen_ctx_dec(), FTRACE_STACK_SKIP);
 }
 
 static void
diff --git a/samples/ftrace/sample-trace-array.c b/samples/ftrace/sample-trace-array.c
index dac67c367457..4147616102f9 100644
--- a/samples/ftrace/sample-trace-array.c
+++ b/samples/ftrace/sample-trace-array.c
@@ -112,7 +112,7 @@ static int __init sample_trace_array_init(void)
 	/*
 	 * If context specific per-cpu buffers havent already been allocated.
 	 */
-	trace_printk_init_buffers();
+	trace_array_init_printk(tr);
 
 	simple_tsk = kthread_run(simple_thread, NULL, "sample-instance");
 	if (IS_ERR(simple_tsk)) {

Re: [GIT PULL] tracing: Fixes for v6.15

[pr-tracker-bot]

The pull request you sent on Wed, 14 May 2025 13:58:39 -0400:

> git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git trace-v6.15-rc6

has been merged into torvalds/linux.git:
https://git.kernel.org/torvalds/c/c94d59a126cb9a8d1f71e3e044363d654dcd7af8

Thank you!

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